This invention relates to improved power driven pipe spinners for rapidly rotating a pipe, such as a section of a drill string, to connect one pipe section to or disconnect it from another section.
In removing a string of drill pipe from a well, or lowering it back into the well, the numerous threaded connections in the string must be disconnected or connected as rapidly as possible in order to avoid unnecessary loss of rig time and minimize the cost of the overall drilling operation. To assist in such disconnection and connection of the threaded joints, power spinners have been devised which are capable of turning a pipe section rapidly in either direction relative to another section. A well known type of spinner currently in use includes a series of rollers adapted to engage a well pipe at different locations about its periphery in a relation gripping the pipe between the rollers and then driving it rotatively by powered rotation of one or more of the rollers. Some of the rollers are relatively movable between closed positions for contacting and gripping the pipe and open positions in which the rollers are spaced sufficiently to enable the tool to be moved between an active position about the pipe and a retracted position offset to a side of the pipe.